Running 128t, 64t, & 32t, on 16 thread cpu

Message boards : Number crunching : Running 128t, 64t, & 32t, on 16 thread cpu
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Profile Petrctale
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Message 1807 - Posted: 20 Dec 2024, 17:56:27 UTC

I know it's possible to run Run 128t, 64t, & 32t, on a 16 thread cpu. Im looking for the information needed in the app.config.xml file.

Is doing this a wise idea?
Will it take forever to complete?
Instructions, ideas< comments, or any information would be appreciated.
Thanks

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Message 1808 - Posted: 20 Dec 2024, 21:08:35 UTC - in response to Message 1807.  
Last modified: 20 Dec 2024, 21:12:17 UTC

This should be the solution:
https://boinc.berkeley.edu/wiki/Client_configuration
file: cc_config.xml
section: <options>
field: <ncpus>N</ncpus>
default: -1
description: Act as if there were N CPUs; e.g. to simulate 2 CPUs on a machine that has only 1. Zero means use the actual number of CPUs. Don't use this to limit CPU usage; use computing preferences instead.
It doesn't seem to be possible to raise the simulated core count just for specific projects, only for the whole client.
As long as only yafu is running and all the individual threads are able to run without other hard bottlenecks like RAM this shoudn't be a problem.
I suspect that they will fight a little for the real cpu cores with additional context switching, but in general I just expect a scaling of the runtime.
Eg. 128t tasks could take a bit over 8 times as long as 16t tasks.
More detailled, the unknown factor will be the context switch frequency, the CPU cache reloading time and the amount of CPU cycles this will steal, to cram 128 threads one after another into the 12 real cores of your CPU, while 16 threads can run simultaneously and 112 are suspended at every moment... should be interesting!
https://www.youtube.com/watch?v=LDhoD4IVElk
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Message 1886 - Posted: 17 Nov 2025, 19:00:49 UTC

I'm a little late updating progress but thought I post anyway changing ncpus 128; 64; 32; works great and doesn't seem to run excessively long.

Thanks again

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Message boards : Number crunching : Running 128t, 64t, & 32t, on 16 thread cpu




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